Disk Quotas and Free Space

Disk quotas are transparent to the user. When a user asks how much space is free on a disk, the system reports only the user's available quota allowance. If the user exceeds this allowance, the system indicates that the disk is full.

To obtain more free disk space after exceeding the quota allowance, the user must do one of the following:

• Delete files.
• Have another user claim ownership of some files.
• Have the administrator increase the quota allowance.

The following conditions apply when you use disk quotas:

• Disk quotas set on a volume apply only to that volume.
• Disk quotas cannot be set on individual files or folders.
• Disk quotas are based on uncompressed file sizes. You cannot increase the amount of free space by compressing the data.
• If your computer is configured as a multiple-boot system with Windows 2000 and Windows NT 4.0, you can exceed your limit when you are running Windows NT 4.0. However, when you are running Windows 2000, you must move files to a different partition or delete files until you are under your limit.
• To support disk quotas, a disk volume must be formatted with NTFS. Volumes formatted with previous versions of NTFS are upgraded automatically by Windows 2000 Setup.
• To administer quotas on a volume, you must be a member of the Administrators group on the computer where the drive resides.
• If the volume is not formatted with NTFS, or if you are not a member of the Administrators group on the local computer, the Quota tab is not displayed on the volume's Properties page.

Disk Quota Limits

The disk space used by each file is charged directly to the user who owns the file. The file owner is identified by the security identifier (SID) in the security information for the file. The total disk space charged to a user is the sum of the length of all data streams, and property set streams and resident user data streams affect the user's quota. Compressing or decompressing files does not affect the disk space reported for the files. Therefore, quota settings on one volume can be compared to settings on another volume.

The following are types of disk quota limits.

Warning threshold   You can configure the system to generate a system log file entry when the disk space charged to the user exceeds this value.

Hard quota   You can configure the system to generate a system log file entry or deny additional disk space to the user when the disk space charged to the user exceeds this value.

NTFS automatically creates a user quota entry when a user first writes to the volume. Entries that are created automatically are assigned the default warning threshold and hard quota limit values for the volume.

Disk Quotas States

The administrator can turn quota enforcement on and off. There are three quota states, as shown in Table 2.13.

Table 2.13 Disk Quota States

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